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-rw-r--r--src/script/bitcoinconsensus.cpp2
-rw-r--r--src/script/bitcoinconsensus.h1
-rw-r--r--src/script/interpreter.cpp176
-rw-r--r--src/script/interpreter.h26
-rw-r--r--src/script/script.h2
-rw-r--r--src/script/script_error.h1
-rw-r--r--src/script/sigcache.cpp4
-rw-r--r--src/script/sigcache.h4
-rw-r--r--src/script/sign.cpp4
-rw-r--r--src/script/standard.h8
10 files changed, 133 insertions, 95 deletions
diff --git a/src/script/bitcoinconsensus.cpp b/src/script/bitcoinconsensus.cpp
index c8dd54a74..b0d5faaf7 100644
--- a/src/script/bitcoinconsensus.cpp
+++ b/src/script/bitcoinconsensus.cpp
@@ -78,7 +78,7 @@ int bitcoinconsensus_verify_script(const unsigned char *scriptPubKey, unsigned i
// Regardless of the verification result, the tx did not error.
set_error(err, bitcoinconsensus_ERR_OK);
- return VerifyScript(tx.vin[nIn].scriptSig, CScript(scriptPubKey, scriptPubKey + scriptPubKeyLen), flags, SignatureChecker(tx, nIn), NULL);
+ return VerifyScript(tx.vin[nIn].scriptSig, CScript(scriptPubKey, scriptPubKey + scriptPubKeyLen), flags, TransactionSignatureChecker(&tx, nIn), NULL);
} catch (const std::exception&) {
return set_error(err, bitcoinconsensus_ERR_TX_DESERIALIZE); // Error deserializing
}
diff --git a/src/script/bitcoinconsensus.h b/src/script/bitcoinconsensus.h
index 9d9c26643..032057779 100644
--- a/src/script/bitcoinconsensus.h
+++ b/src/script/bitcoinconsensus.h
@@ -46,6 +46,7 @@ enum
{
bitcoinconsensus_SCRIPT_FLAGS_VERIFY_NONE = 0,
bitcoinconsensus_SCRIPT_FLAGS_VERIFY_P2SH = (1U << 0), // evaluate P2SH (BIP16) subscripts
+ bitcoinconsensus_SCRIPT_FLAGS_VERIFY_DERSIG = (1U << 2), // enforce strict DER (BIP66) compliance
};
/// Returns 1 if the input nIn of the serialized transaction pointed to by
diff --git a/src/script/interpreter.cpp b/src/script/interpreter.cpp
index 80a32e78f..84a7432fd 100644
--- a/src/script/interpreter.cpp
+++ b/src/script/interpreter.cpp
@@ -60,7 +60,7 @@ bool CastToBool(const valtype& vch)
static inline void popstack(vector<valtype>& stack)
{
if (stack.empty())
- throw runtime_error("popstack() : stack empty");
+ throw runtime_error("popstack(): stack empty");
stack.pop_back();
}
@@ -93,76 +93,76 @@ bool static IsCompressedOrUncompressedPubKey(const valtype &vchPubKey) {
* in which case a single 0 byte is necessary and even required).
*
* See https://bitcointalk.org/index.php?topic=8392.msg127623#msg127623
+ *
+ * This function is consensus-critical since BIP66.
*/
-bool static IsDERSignature(const valtype &vchSig) {
+bool static IsValidSignatureEncoding(const std::vector<unsigned char> &sig) {
+ // Format: 0x30 [total-length] 0x02 [R-length] [R] 0x02 [S-length] [S] [sighash]
+ // * total-length: 1-byte length descriptor of everything that follows,
+ // excluding the sighash byte.
+ // * R-length: 1-byte length descriptor of the R value that follows.
+ // * R: arbitrary-length big-endian encoded R value. It must use the shortest
+ // possible encoding for a positive integers (which means no null bytes at
+ // the start, except a single one when the next byte has its highest bit set).
+ // * S-length: 1-byte length descriptor of the S value that follows.
+ // * S: arbitrary-length big-endian encoded S value. The same rules apply.
+ // * sighash: 1-byte value indicating what data is hashed (not part of the DER
+ // signature)
- if (vchSig.size() < 9) {
- // Non-canonical signature: too short
- return false;
- }
- if (vchSig.size() > 73) {
- // Non-canonical signature: too long
- return false;
- }
- if (vchSig[0] != 0x30) {
- // Non-canonical signature: wrong type
- return false;
- }
- if (vchSig[1] != vchSig.size()-3) {
- // Non-canonical signature: wrong length marker
- return false;
- }
- unsigned int nLenR = vchSig[3];
- if (5 + nLenR >= vchSig.size()) {
- // Non-canonical signature: S length misplaced
- return false;
- }
- unsigned int nLenS = vchSig[5+nLenR];
- if ((unsigned long)(nLenR+nLenS+7) != vchSig.size()) {
- // Non-canonical signature: R+S length mismatch
- return false;
- }
+ // Minimum and maximum size constraints.
+ if (sig.size() < 9) return false;
+ if (sig.size() > 73) return false;
- const unsigned char *R = &vchSig[4];
- if (R[-2] != 0x02) {
- // Non-canonical signature: R value type mismatch
- return false;
- }
- if (nLenR == 0) {
- // Non-canonical signature: R length is zero
- return false;
- }
- if (R[0] & 0x80) {
- // Non-canonical signature: R value negative
- return false;
- }
- if (nLenR > 1 && (R[0] == 0x00) && !(R[1] & 0x80)) {
- // Non-canonical signature: R value excessively padded
- return false;
- }
+ // A signature is of type 0x30 (compound).
+ if (sig[0] != 0x30) return false;
+
+ // Make sure the length covers the entire signature.
+ if (sig[1] != sig.size() - 3) return false;
+
+ // Extract the length of the R element.
+ unsigned int lenR = sig[3];
+
+ // Make sure the length of the S element is still inside the signature.
+ if (5 + lenR >= sig.size()) return false;
+
+ // Extract the length of the S element.
+ unsigned int lenS = sig[5 + lenR];
+
+ // Verify that the length of the signature matches the sum of the length
+ // of the elements.
+ if ((size_t)(lenR + lenS + 7) != sig.size()) return false;
+
+ // Check whether the R element is an integer.
+ if (sig[2] != 0x02) return false;
+
+ // Zero-length integers are not allowed for R.
+ if (lenR == 0) return false;
+
+ // Negative numbers are not allowed for R.
+ if (sig[4] & 0x80) return false;
+
+ // Null bytes at the start of R are not allowed, unless R would
+ // otherwise be interpreted as a negative number.
+ if (lenR > 1 && (sig[4] == 0x00) && !(sig[5] & 0x80)) return false;
+
+ // Check whether the S element is an integer.
+ if (sig[lenR + 4] != 0x02) return false;
+
+ // Zero-length integers are not allowed for S.
+ if (lenS == 0) return false;
+
+ // Negative numbers are not allowed for S.
+ if (sig[lenR + 6] & 0x80) return false;
+
+ // Null bytes at the start of S are not allowed, unless S would otherwise be
+ // interpreted as a negative number.
+ if (lenS > 1 && (sig[lenR + 6] == 0x00) && !(sig[lenR + 7] & 0x80)) return false;
- const unsigned char *S = &vchSig[6+nLenR];
- if (S[-2] != 0x02) {
- // Non-canonical signature: S value type mismatch
- return false;
- }
- if (nLenS == 0) {
- // Non-canonical signature: S length is zero
- return false;
- }
- if (S[0] & 0x80) {
- // Non-canonical signature: S value negative
- return false;
- }
- if (nLenS > 1 && (S[0] == 0x00) && !(S[1] & 0x80)) {
- // Non-canonical signature: S value excessively padded
- return false;
- }
return true;
}
bool static IsLowDERSignature(const valtype &vchSig, ScriptError* serror) {
- if (!IsDERSignature(vchSig)) {
+ if (!IsValidSignatureEncoding(vchSig)) {
return set_error(serror, SCRIPT_ERR_SIG_DER);
}
unsigned int nLenR = vchSig[3];
@@ -189,7 +189,12 @@ bool static IsDefinedHashtypeSignature(const valtype &vchSig) {
}
bool static CheckSignatureEncoding(const valtype &vchSig, unsigned int flags, ScriptError* serror) {
- if ((flags & (SCRIPT_VERIFY_DERSIG | SCRIPT_VERIFY_LOW_S | SCRIPT_VERIFY_STRICTENC)) != 0 && !IsDERSignature(vchSig)) {
+ // Empty signature. Not strictly DER encoded, but allowed to provide a
+ // compact way to provide an invalid signature for use with CHECK(MULTI)SIG
+ if (vchSig.size() == 0) {
+ return true;
+ }
+ if ((flags & (SCRIPT_VERIFY_DERSIG | SCRIPT_VERIFY_LOW_S | SCRIPT_VERIFY_STRICTENC)) != 0 && !IsValidSignatureEncoding(vchSig)) {
return set_error(serror, SCRIPT_ERR_SIG_DER);
} else if ((flags & SCRIPT_VERIFY_LOW_S) != 0 && !IsLowDERSignature(vchSig, serror)) {
// serror is set
@@ -1030,16 +1035,17 @@ public:
uint256 SignatureHash(const CScript& scriptCode, const CTransaction& txTo, unsigned int nIn, int nHashType)
{
+ static const uint256 one(uint256S("0000000000000000000000000000000000000000000000000000000000000001"));
if (nIn >= txTo.vin.size()) {
// nIn out of range
- return 1;
+ return one;
}
// Check for invalid use of SIGHASH_SINGLE
if ((nHashType & 0x1f) == SIGHASH_SINGLE) {
if (nIn >= txTo.vout.size()) {
// nOut out of range
- return 1;
+ return one;
}
}
@@ -1052,12 +1058,12 @@ uint256 SignatureHash(const CScript& scriptCode, const CTransaction& txTo, unsig
return ss.GetHash();
}
-bool SignatureChecker::VerifySignature(const std::vector<unsigned char>& vchSig, const CPubKey& pubkey, const uint256& sighash) const
+bool TransactionSignatureChecker::VerifySignature(const std::vector<unsigned char>& vchSig, const CPubKey& pubkey, const uint256& sighash) const
{
return pubkey.Verify(sighash, vchSig);
}
-bool SignatureChecker::CheckSig(const vector<unsigned char>& vchSigIn, const vector<unsigned char>& vchPubKey, const CScript& scriptCode) const
+bool TransactionSignatureChecker::CheckSig(const vector<unsigned char>& vchSigIn, const vector<unsigned char>& vchPubKey, const CScript& scriptCode) const
{
CPubKey pubkey(vchPubKey);
if (!pubkey.IsValid())
@@ -1070,7 +1076,7 @@ bool SignatureChecker::CheckSig(const vector<unsigned char>& vchSigIn, const vec
int nHashType = vchSig.back();
vchSig.pop_back();
- uint256 sighash = SignatureHash(scriptCode, txTo, nIn, nHashType);
+ uint256 sighash = SignatureHash(scriptCode, *txTo, nIn, nHashType);
if (!VerifySignature(vchSig, pubkey, sighash))
return false;
@@ -1097,7 +1103,6 @@ bool VerifyScript(const CScript& scriptSig, const CScript& scriptPubKey, unsigne
return false;
if (stack.empty())
return set_error(serror, SCRIPT_ERR_EVAL_FALSE);
-
if (CastToBool(stack.back()) == false)
return set_error(serror, SCRIPT_ERR_EVAL_FALSE);
@@ -1108,24 +1113,37 @@ bool VerifyScript(const CScript& scriptSig, const CScript& scriptPubKey, unsigne
if (!scriptSig.IsPushOnly())
return set_error(serror, SCRIPT_ERR_SIG_PUSHONLY);
- // stackCopy cannot be empty here, because if it was the
+ // Restore stack.
+ swap(stack, stackCopy);
+
+ // stack cannot be empty here, because if it was the
// P2SH HASH <> EQUAL scriptPubKey would be evaluated with
// an empty stack and the EvalScript above would return false.
- assert(!stackCopy.empty());
+ assert(!stack.empty());
- const valtype& pubKeySerialized = stackCopy.back();
+ const valtype& pubKeySerialized = stack.back();
CScript pubKey2(pubKeySerialized.begin(), pubKeySerialized.end());
- popstack(stackCopy);
+ popstack(stack);
- if (!EvalScript(stackCopy, pubKey2, flags, checker, serror))
+ if (!EvalScript(stack, pubKey2, flags, checker, serror))
// serror is set
return false;
- if (stackCopy.empty())
+ if (stack.empty())
return set_error(serror, SCRIPT_ERR_EVAL_FALSE);
- if (!CastToBool(stackCopy.back()))
+ if (!CastToBool(stack.back()))
return set_error(serror, SCRIPT_ERR_EVAL_FALSE);
- else
- return set_success(serror);
+ }
+
+ // The CLEANSTACK check is only performed after potential P2SH evaluation,
+ // as the non-P2SH evaluation of a P2SH script will obviously not result in
+ // a clean stack (the P2SH inputs remain).
+ if ((flags & SCRIPT_VERIFY_CLEANSTACK) != 0) {
+ // Disallow CLEANSTACK without P2SH, as otherwise a switch CLEANSTACK->P2SH+CLEANSTACK
+ // would be possible, which is not a softfork (and P2SH should be one).
+ assert((flags & SCRIPT_VERIFY_P2SH) != 0);
+ if (stack.size() != 1) {
+ return set_error(serror, SCRIPT_ERR_CLEANSTACK);
+ }
}
return set_success(serror);
diff --git a/src/script/interpreter.h b/src/script/interpreter.h
index 3c4e7d466..fc64438f6 100644
--- a/src/script/interpreter.h
+++ b/src/script/interpreter.h
@@ -7,6 +7,7 @@
#define BITCOIN_SCRIPT_INTERPRETER_H
#include "script_error.h"
+#include "primitives/transaction.h"
#include <vector>
#include <stdint.h>
@@ -67,8 +68,14 @@ enum
// discouraged NOPs fails the script. This verification flag will never be
// a mandatory flag applied to scripts in a block. NOPs that are not
// executed, e.g. within an unexecuted IF ENDIF block, are *not* rejected.
- SCRIPT_VERIFY_DISCOURAGE_UPGRADABLE_NOPS = (1U << 7)
-
+ SCRIPT_VERIFY_DISCOURAGE_UPGRADABLE_NOPS = (1U << 7),
+
+ // Require that only a single stack element remains after evaluation. This changes the success criterion from
+ // "At least one stack element must remain, and when interpreted as a boolean, it must be true" to
+ // "Exactly one stack element must remain, and when interpreted as a boolean, it must be true".
+ // (softfork safe, BIP62 rule 6)
+ // Note: CLEANSTACK should never be used without P2SH.
+ SCRIPT_VERIFY_CLEANSTACK = (1U << 8),
};
uint256 SignatureHash(const CScript &scriptCode, const CTransaction& txTo, unsigned int nIn, int nHashType);
@@ -84,20 +91,29 @@ public:
virtual ~BaseSignatureChecker() {}
};
-class SignatureChecker : public BaseSignatureChecker
+class TransactionSignatureChecker : public BaseSignatureChecker
{
private:
- const CTransaction& txTo;
+ const CTransaction* txTo;
unsigned int nIn;
protected:
virtual bool VerifySignature(const std::vector<unsigned char>& vchSig, const CPubKey& vchPubKey, const uint256& sighash) const;
public:
- SignatureChecker(const CTransaction& txToIn, unsigned int nInIn) : txTo(txToIn), nIn(nInIn) {}
+ TransactionSignatureChecker(const CTransaction* txToIn, unsigned int nInIn) : txTo(txToIn), nIn(nInIn) {}
bool CheckSig(const std::vector<unsigned char>& scriptSig, const std::vector<unsigned char>& vchPubKey, const CScript& scriptCode) const;
};
+class MutableTransactionSignatureChecker : public TransactionSignatureChecker
+{
+private:
+ const CTransaction txTo;
+
+public:
+ MutableTransactionSignatureChecker(const CMutableTransaction* txToIn, unsigned int nInIn) : TransactionSignatureChecker(&txTo, nInIn), txTo(*txToIn) {}
+};
+
bool EvalScript(std::vector<std::vector<unsigned char> >& stack, const CScript& script, unsigned int flags, const BaseSignatureChecker& checker, ScriptError* error = NULL);
bool VerifyScript(const CScript& scriptSig, const CScript& scriptPubKey, unsigned int flags, const BaseSignatureChecker& checker, ScriptError* error = NULL);
diff --git a/src/script/script.h b/src/script/script.h
index 78fd12cd2..8b36aa2f5 100644
--- a/src/script/script.h
+++ b/src/script/script.h
@@ -391,7 +391,7 @@ public:
CScript& operator<<(opcodetype opcode)
{
if (opcode < 0 || opcode > 0xff)
- throw std::runtime_error("CScript::operator<<() : invalid opcode");
+ throw std::runtime_error("CScript::operator<<(): invalid opcode");
insert(end(), (unsigned char)opcode);
return *this;
}
diff --git a/src/script/script_error.h b/src/script/script_error.h
index 5c260327b..6365680b2 100644
--- a/src/script/script_error.h
+++ b/src/script/script_error.h
@@ -43,6 +43,7 @@ typedef enum ScriptError_t
SCRIPT_ERR_SIG_HIGH_S,
SCRIPT_ERR_SIG_NULLDUMMY,
SCRIPT_ERR_PUBKEYTYPE,
+ SCRIPT_ERR_CLEANSTACK,
/* softfork safeness */
SCRIPT_ERR_DISCOURAGE_UPGRADABLE_NOPS,
diff --git a/src/script/sigcache.cpp b/src/script/sigcache.cpp
index 75ecdb563..099b4ad0e 100644
--- a/src/script/sigcache.cpp
+++ b/src/script/sigcache.cpp
@@ -74,14 +74,14 @@ public:
}
-bool CachingSignatureChecker::VerifySignature(const std::vector<unsigned char>& vchSig, const CPubKey& pubkey, const uint256& sighash) const
+bool CachingTransactionSignatureChecker::VerifySignature(const std::vector<unsigned char>& vchSig, const CPubKey& pubkey, const uint256& sighash) const
{
static CSignatureCache signatureCache;
if (signatureCache.Get(sighash, vchSig, pubkey))
return true;
- if (!SignatureChecker::VerifySignature(vchSig, pubkey, sighash))
+ if (!TransactionSignatureChecker::VerifySignature(vchSig, pubkey, sighash))
return false;
if (store)
diff --git a/src/script/sigcache.h b/src/script/sigcache.h
index 3bd11caff..b299038da 100644
--- a/src/script/sigcache.h
+++ b/src/script/sigcache.h
@@ -12,13 +12,13 @@
class CPubKey;
-class CachingSignatureChecker : public SignatureChecker
+class CachingTransactionSignatureChecker : public TransactionSignatureChecker
{
private:
bool store;
public:
- CachingSignatureChecker(const CTransaction& txToIn, unsigned int nInIn, bool storeIn=true) : SignatureChecker(txToIn, nInIn), store(storeIn) {}
+ CachingTransactionSignatureChecker(const CTransaction* txToIn, unsigned int nInIn, bool storeIn=true) : TransactionSignatureChecker(txToIn, nInIn), store(storeIn) {}
bool VerifySignature(const std::vector<unsigned char>& vchSig, const CPubKey& vchPubKey, const uint256& sighash) const;
};
diff --git a/src/script/sign.cpp b/src/script/sign.cpp
index adddd4ec7..14119f7e2 100644
--- a/src/script/sign.cpp
+++ b/src/script/sign.cpp
@@ -123,7 +123,7 @@ bool SignSignature(const CKeyStore &keystore, const CScript& fromPubKey, CMutabl
}
// Test solution
- return VerifyScript(txin.scriptSig, fromPubKey, STANDARD_SCRIPT_VERIFY_FLAGS, SignatureChecker(txTo, nIn));
+ return VerifyScript(txin.scriptSig, fromPubKey, STANDARD_SCRIPT_VERIFY_FLAGS, MutableTransactionSignatureChecker(&txTo, nIn));
}
bool SignSignature(const CKeyStore &keystore, const CTransaction& txFrom, CMutableTransaction& txTo, unsigned int nIn, int nHashType)
@@ -174,7 +174,7 @@ static CScript CombineMultisig(const CScript& scriptPubKey, const CTransaction&
if (sigs.count(pubkey))
continue; // Already got a sig for this pubkey
- if (SignatureChecker(txTo, nIn).CheckSig(sig, pubkey, scriptPubKey))
+ if (TransactionSignatureChecker(&txTo, nIn).CheckSig(sig, pubkey, scriptPubKey))
{
sigs[pubkey] = sig;
break;
diff --git a/src/script/standard.h b/src/script/standard.h
index 1d29ef57a..a8b0acc98 100644
--- a/src/script/standard.h
+++ b/src/script/standard.h
@@ -20,12 +20,12 @@ class CScript;
class CScriptID : public uint160
{
public:
- CScriptID() : uint160(0) {}
+ CScriptID() : uint160() {}
CScriptID(const CScript& in);
CScriptID(const uint160& in) : uint160(in) {}
};
-static const unsigned int MAX_OP_RETURN_RELAY = 40; //! bytes
+static const unsigned int MAX_OP_RETURN_RELAY = 80; //! bytes
extern unsigned nMaxDatacarrierBytes;
/**
@@ -45,10 +45,12 @@ static const unsigned int MANDATORY_SCRIPT_VERIFY_FLAGS = SCRIPT_VERIFY_P2SH;
* blocks and we must accept those blocks.
*/
static const unsigned int STANDARD_SCRIPT_VERIFY_FLAGS = MANDATORY_SCRIPT_VERIFY_FLAGS |
+ SCRIPT_VERIFY_DERSIG |
SCRIPT_VERIFY_STRICTENC |
SCRIPT_VERIFY_MINIMALDATA |
SCRIPT_VERIFY_NULLDUMMY |
- SCRIPT_VERIFY_DISCOURAGE_UPGRADABLE_NOPS;
+ SCRIPT_VERIFY_DISCOURAGE_UPGRADABLE_NOPS |
+ SCRIPT_VERIFY_CLEANSTACK;
/** For convenience, standard but not mandatory verify flags. */
static const unsigned int STANDARD_NOT_MANDATORY_VERIFY_FLAGS = STANDARD_SCRIPT_VERIFY_FLAGS & ~MANDATORY_SCRIPT_VERIFY_FLAGS;
generated by cgit v1.2.3 (git 2.25.1) at 2026-04-29 07:36:30 +0000